Tools should explain why an option is bad when using fmsg_bad_option.
Add an explanation of why an option was bad to fmsg_bad_option calls that
were just using "" as argument. Fixes bug #334802.
git-svn-id: svn://svn.valgrind.org/valgrind/trunk@13975 a5019735-40e9-0310-863c-91ae7b9d1cf9